What is the ruling on reciting Surat Al-Fath 141 times to relieve worries and problems, and has a hadith been narrated to that effect?

There is no hadith indicating a specific number of Qur'an recitations for a particular purpose, even though reciting the Qur'an carries immense reward. This practice might stem from the experience or ijtihad (independent reasoning) of some later scholars. Goodness lies in following what was known and practiced by the early generations (salaf) of the Ummah; they were the most knowledgeable concerning what is good, and the fundamental principle in acts of worship is tawqif (that they are legislated by divine texts and not by human reasoning).